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  <title>绝对定位</title>
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  <link rel="stylesheet" href="css/abs.css">
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  <div class="border-box box01">绝对定位的参照物</div>

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    <div class="border-box box02">慎用绝对定位</div>
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    <div>被约束的绝对定位</div>
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  <div class="box04 border-box">
    <div>1</div>
    <div>2</div>
    <div>3</div>
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  <div class="border-box box05">
    <div>页面内容<br>内容和内容</div>
    <div>99</div>
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  <div class="border-box box06">
    <div>这里是正常的内容</div>
    <div>整块全遮罩</div>
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